1. Field of the Invention
The invention concerns the preparation of beverages or the like from an extraction material contained in a capsule, for example ground coffee. In particular, the invention concerns a pierceable capsule as a portion pack, and a method for producing the same.
2. Description of Related Art
Extraction devices for preparing beverages from an extraction material supplied in a portion pack are known, for example, as coffee or espresso machines and continue to enjoy increasing popularity. In many such systems, the portion packs are designed as capsules in which the extraction material is encased, for example in an airtight manner. For the purpose of extraction, the capsule is pierced from two opposite sides. An extraction liquid—generally hot water—is introduced on the first side. The extraction product is discharged from the capsule on the second side. In such a case, a considerable pressure, for example of 5-20 bar, must prevail in the interior of the capsule.
Aluminum and plastics, for example polypropylene, have become most commonly used as capsule materials. Aluminum capsules keep the extraction material fresh for a long time, but require a considerable amount of energy in respect of production. Polypropylene capsules are advantageous in respect of energy consumption and disposal, but impose a greater challenge to the piercing mechanism.
Both, capsules with integrated filtering means and capsules merely encasing the extraction material are commercially available. In the latter case, the piercing mechanism needs to be designed in a manner preventing the extraction material escaping from the capsule together with the extraction product.
An example of a capsule without integrated filtering means is disclosed in EP 1 886 942, for example.
EP 1 344 722 discloses a cup-shaped capsule. The capsule according to these specifications comprises an internal distribution or collection element, which separates a first region of the capsule, which region is to be filled with water or the beverage, from a second region containing the extraction material. The distribution or collection element is provided with a large number of channels for distributing the water or for collecting the beverage, and is designed and arranged in such a manner that it is not pierced by the perforation means of the coffee machine.
Capsules with an integrated filter are also known, for example from US 2005/0051478. The filter performs the function of a paper filter of a known filter coffee machine: water is injected into that region of the capsule, which contains the extraction material, by a piercing spike at a low pressure or at zero pressure. After the extraction process, the coffee passes through the capsule's own paper filter into a collection region, where it is collected by a further piercing spike.
WO 2008/011913 discloses a capsule comprising an outlet closed by a “crema” forming web. It further comprises a safety lid with a shoulder retaining the web. On the side opposite the outlet, there is a lid forming a ring-shaped recess around an inlet.
Filter coffee continues to be very popular in many regions and cups are often filled with large portions of up to 0.3 or 0.4 liters of filter coffee. For the preparation of such portions from capsules, commonly known portion capsules that are designed to hold no more than 6 to 8 g coffee, is often insufficient. Therefore, coffee machines using portion capsules are not very widespread in markets where filter coffee is popular. Where they are used, however, the capsules are considerably larger than the known capsules of capsule systems intended for preparing espresso. The coffee machines comprise a relatively large brewing chamber which is adapted for relatively large portion capsules and comprise a pump designed accordingly for delivering relatively large amounts of hot water at a low pressure. Therefore, these coffee machines are not suitable for brewing espresso.
However, it would be advantageous if filter coffee lovers could also use the available means to brew an espresso if desired.